Thermal cutout for flatirons or the like



CUTOUT FOR FLATIRONS OR THE LIKE THERMAL Filed June 26, 1948 v/z a /r/ .3 (1L) 7 l 1 z 39 30g 36 3a 3 Inventor:

AlFred G. Swanson b y mttormey Patented Oct. 31, 1950 [THERMAL CUTOUT FOR FLATIRONS OR THE LIKE Alfred ,G. S wenson, Ontario, .Califi, .assignorrto General, Electric Company, .a corporation of New York Application June 26, 1948,-'Serial N;'35,335

ZCIaims. (01-21945) 1My;i nvention relates to; improvements in thermostats ,orcutouts for heating devices such as electric fiatirons. qAmongqthe objectsof myyinvention are to make an inexpensive cutoutwhich easy to manufacture, reliable .in operation, and capable of withstanding rough usage.

Many cutouts for flatirons prior to .myinvention have suffered from .the disadvantage that -.they-,are subject to overshoot, i. e., th ;temperature of the iron will-continue torise to an undesirable degree after the protective cutout has opened the circuit to thejheating element of -the iron. One of thespeoific advantages of .myinvention is the alleviation of thiscondition ,while accomplishing the primary objects mentioned above.

Th objects and advantages desired-are .ob-

tained notonly by .the particular design ofzthe thermostat or cut0ut,-itself,'but :also by the mannerandplace of mounting the cutout with relation to other parts of th iron orother heating ,device. Details of that which .I, believe -to be novel and my invention .will be clear ;from the following description and .claims taken with the accompanying drawing in which isillustratedas an example, a flatiron with improved cutout mounted so as to obtain the-desirable objects and advantages noted.

In the drawing, Fig. 1 is a-sectional side view of an iron; Fig. 2 is a plan View of the iron of Fig. 1 with some of the top parts of the iron partly broken away to show the cutout and its mounti g; Fig. 3 is a section substantially on the line and in the direction indicated at 33 in Fig. 1,showing the cutout and its mounting in elevation; and Fig. 4 is an enlarged cross section of the cutout, with a wiring diagram.

The construction of the particular iron shown and described here is not my invention, but .is shown, described and claimed in the copending application of Frank E. Finlayson for Inexpensive Electric Flatiron, Serial No. 35,400, filed June 26, 1948, and assigned to the same assignee asthe present application. For purposes of the present disclosure, and to illustrate an example of preferred construction in which my cutout may be used and mounted, th iron proper. will be described first, and the thermal cutout of my invention will then be described in relationt parts of the exemplary iron.

The principal part of the iron isthe sole iiblock I, made of cast aluminum or other metal. The block is provided with a bottom ironing face 2, and two converging side faces 3, which meet at th too 4 of the block. Joining th rear ends ofthe side facesis a -back facet. A=fiat top face 6 completes theouter surfaces of -the sole zblock.

:In the top facet-a cavity! isprovided in .which'the heater terminals, the power connections and theacutoutwill be securedcand positioned. as .later described. This cavityalsdextends and .opensxintothe back face of the 7 block,

Forsupplying heat to the iron, a :heating .element.8 issprovided. Thiselementis embedded in :the :block I around the :cavity and is preferably of th substantially rigid, self-.insulated type vin .order to :bestntilizesmy invention. Such a heating element may .be .;of .the character patented .by.:C..C. Abbott, No..1:,36'l,3410on Februarysl, 1921 It ;.has a helical resistance .conductor '9 .housed within .a metallic sheath .IIO with .ahighly compaoted heat. conducting. and electrical insulating material .l.| suchzas powdered magnesium oxide, to. support .the .conductoriinspaced relation within .thesheath. The'iterminahsections of this heater are provided with the usual -rigid.;and self -supporting wireleads ZWhlChfiIe .connected to the internal resistance-conductor.in the usual fashion and are insulated fromthe endsof the metallic sheath :by the compacted insulating ma- .terial II. .Washerslii, preferably of .mica or similar insulating material, :may assist .in the insulation of the wire lead terminals :from the sheath.

Because the heater'is :embedded in -the block and issubstantiallyrigid, and the terminalsl2 extend into the cavity of the :blockopposite the opening in the .back :face of the block, these .terminals maybe described .:as iselfe'supporting. No outside support for the free wends of the-heater is required. .1

Closing the-top ofthe cavity in-the sole block, and housing the' terminals and the cutout, isa cover'plate I 4. This cover carries a front handle post l 5, and is provided with -a rolled back edge 16 which may form part of a heel stand for'the iron when the ironis at rest. This 'cover' plate may be held'in 'placeby suitable means such as a screw ,li'l, threaded into the block directly," and by .a screw 18 which is threaded into a'support I9. This support iss'hown as secured by screws 20 to the block, and bridges the cavity in the iron. v v

Conventional plug terminals M and 22;; are provided, and these are conveniently carried by but insulated from the support l9 in a manner readily understood. These plug terminals are adapted to be connected to a source of electrical 3 power through the usual appliance cord and plug, not shown.

A back cover 23 for the back face opening is provided, and this may be made as a part of the support member. Ears 24 on the support can serve to position the cover plate on th sole block and to hold it in slightly spaced relation therefrom.

A plug guard 25, carrying a rear handle post 26, is shown as secured to the support 19 by a ledge 21 which extends under the edge of a hole 28 in the cover plate, being held in place by the screw [8.

Completing the iron is a hand gripALfastened Contributing to the accurate response of the? thermostat to heating changes within the exemplary iron are other factors, such as the absence of physical support of the cutout by other and possibly cooler parts of the iron, the position of the bimetal between the legs formed by thecurrent-carrying frame and the sprin arm,

the mounting of the cutout in the cavity between the heated side walls and bottom face of the iron, and the substantially complete enclosure of the space in which the cutout is mounted.

Obviously, forms of irons other than the one shown, and heating devices other than flatirons, may be provided with the thermal cutout of my invention to advantage. The device described here, however, has all of the structures necessary for the complete utilization of my invention in the heating unit or sole block from overheating;

the cutout and its mounting of my invention were specifically, designed. This thermally responsive cutout or thermostat is generally indicated at 29. This cutout has a current-carrying frame 30, one end of which is attached directly to one of the heater terminals, as by brazing. -A contact 3i is attached to the other end of the frame member. Cooperating with this first contact is another contact 32 carried by a spring arm 33 which in turn is carried by,,but insulated from, the frame member by insulation piece 34. This piece, which ma be of .mica, also insulates the small bi-metallic piece 35 from the frame, and is held in place together with the .spring arm by rivet 36. Naturally, the spring arm resiliently urges the contacts 3| and 32 toward each other. The terminal rivet 36.mechanically holds the parts together, and connects the. fixed end of the spring arm electrically to.a:wire 3? leading to the plu connectionterminal 2l,.-the rivet passing through but being insulatedfrom the current-carrying frame. 30, as by: the mica washer 38. i The other plug. connection terminal 22 is electrically connected directly to the other. heater terminal by wire 39. A circuit through the device will be completedfrom the plug terminal 2| through the wire 31, the rivet 3.6, the spring arm 33, the. contacts 32 and 31,.theframe ,30, the heater terminal 12, the resistance ;wire::.9 of the heater, the other heater terminal l2,'.-the wire 39, and the plug terminal 22. In operation, the bimetallic strip 35,.- when heated; will, flex in a direction toward the spring arm., Any satisfactory adjusting means, such assetscrew w, mounted in the spring arm, may be used to adjust the setting of thethermostat. The bimetal will bear against the endsof-the screw and flex the spring, arm to open the .contacts when a desired heat has been reached. The above-described thermally-responsivecut out arrangement has been found. 1nate1'ially to reduce overshoot commonly encountered in the control of heating devices of this character. A major part of this result, I believe, is due'to the mounting of the current-carryin frame di' rectly on the heating unit terminal. This mounting permits direct heat conduction from the heater to the thermostat, thereby "reducing the usual time 1ag-between the reaching of a particular heat by the heater and the response by the cutout.

its presently preferred form.

As will be evident from the foregoing description, certain aspects of my invention are not limited to the particular details of construction of the example illustrated, and I contemplate that various and other modifications and applications of the invention will occur to those skilled in the art. It is, therefore, my intention'that the appended claims shall cover such modifications and applications as do not depart from the true spirit and scope of my invention. I

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In an electric heating device of the type including a block with a heater thereon having self-supporting terminals extending into anenclosed cavity in the said device, thatimprovement in cutouts which comprises a current-carrying frame electrically and mechanically connected to and supported entirely by a terminal of the heater and entirely within-the cavity, a spring arm carried by but insulated from said frame, a, thermally movable member supported and extending between the frame and the arm adapted to engage and move the arm when the member is-heated, cooperating normally engaged contacts on the frame and on the arm actuated by movement of the arm upon movement of the member, and a circuit connection from said arm to a power source.

2. An electric fiatiron comprising a sole block, said block having a cavity therein, a heater'embedded in the block around the cavity, a cover for the cavity, rigid self-supporting terminals extending from the heater into the cavity under the cover, a thermally-responsive cutout electrically connected to and mechanically entirely supported by one of the'terminals and located entirely within the cavity, and electrical con nections from the cutout and from the other terminal extending outside of the cavity through the cover.

" ALFRED G. SWENSONL'T REFERENCES CITED The following references are of record in the me ofthispatent:

UNITED STATES PATENTS 2,385,606 Campbell Sept. 25,1945 

